Date:   Wed, 02 Nov 2016 08:58:38 +0100
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Linux PM list <linux-pm@...r.kernel.org>,
        Alan Stern <stern@...land.harvard.edu>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Mark Brown <broonie@...nel.org>,
        Lukas Wunner <lukas@...ner.de>,
        Kevin Hilman <khilman@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        "Luis R. Rodriguez" <mcgrof@...e.com>,
        Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH v6 0/5] Functional dependencies between devices

Hi Greg,


On 2016-10-31 18:47, Greg Kroah-Hartman wrote:
> On Sun, Oct 30, 2016 at 05:22:13PM +0100, Rafael J. Wysocki wrote:
>> Let me quote from the previous intro messages for this series first:
>>
>>>> Time for another update. :-)
>>>>
>>>> Fewer changes this time, mostly to address issues found by Lukas and
>>>> Marek.
>>>>
>>>> The most significant one is to make device_link_add() cope with the case
>>>> when
>>>> the consumer device has not been registered yet when it is called.  The
>>>> supplier device still is required to be registered and the function will
>>>> return NULL if that is not the case.
>>>>
>>>> Another significant change is in patch [4/5] that now makes the core apply
>>>> pm_runtime_get_sync()/pm_runtime_put() to supplier devices around the
>>>> probing of a consumer one (in analogy with the parent).
>>> One more update after some conversations during LinuxCon Europe.
>>>
>>> The main point was to make it possible for device_link_add() to figure out
>>> the initial state of the link instead of expecting the caller to provide it
>>> which might not be reliable enough in general.
>>>
>>> In this version device_link_add() takes three arguments, the supplier and
>>> consumer pointers and flags and it sets the correct initial state of the
>>> link automatically (unless invoked with the "stateless" flag, of course).
>>> The cost is one additional field in struct device (I moved all of the
>>> links-related fields in struct device to a separate sub-structure while at
>>> it) to track the "driver presence status" of the device (to be used by
>>> device_link_add()).
>>>
>>> In addition to that, the links list walks in the core.c and dd.c code are
>>> under the device links mutex now, so the iternal link spinlock is not needed
>>> any more and I have renamed symbols to distinguish between flags, link
>>> states and device "driver presence statuses".
>> The most significant change in this revision with respect to the previous one is
>> related to the fact that SRCU is not available on some architectures, so the
>> code falls back to using an RW semaphore for synchronization if SRCU is not
>> there.  Fortunately, the code changes needed for that turned out to be quite
>> straightforward and confined to the second patch.
>>
>> Apart from this, the flags are defined using BIT(x) now (instead of open coding
>> the latter in the flag definitions).
>>
>> Updated is mostly patch [2/5].  Patches [1,3,5/5] have not changed (except for
>> trivial rebasing) and patch [4/5] needed to be refreshed on top of the modified
>> [2/5].
>>
>> FWIW, I've run the series through 0-day which has not reported any problems
>> with it.
> Great, they are now applied to my tree, thanks again for doing this
> work.

Thanks for merging those patches! Could you provide a stable tag with 
them, so I can
ask Joerg to merge my Exynos IOMMU PM patches on top of it via IOMMU tree?

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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